The invention relates to a control device for operating a load circuit having at least one electric motor, the control device comprising a control stage which generates a pulse width modulated control signal, a power stage supplying the load circuit and having an electronic switch activated by the pulse width modulated control signal, a freewheeling element connected in parallel to the load circuit and a blocking monitoring means which generates a measurement switch-off interval by suppressing at least one switch-on interval of the pulse width modulated control signal, monitors the voltage in the load circuit within the measurement switch-off interval, compares this to a limit value and generates a blocking state signal in accordance with the comparison.
It is only possible with this solution known from the state of the art to detect or not detect whether a voltage has occurred in the load circuit during the measurement switch-off interval on account of the overall voltage monitoring in the load circuit.
If, however, the load circuit comprises not only one electric motor but rather two electric motors, a voltage which is generated by the electric motor which is not blocked still occurs in the load circuit even when one of the two electric motors is blocked. The object underlying the invention is therefore to improve a control device of the type described at the outset in such a manner that a differentiated analysis of the voltages occurring in the measurement switch-off interval is possible.